I was at one of my favorite old junkyards yesterday and noticed someone pulled the heads from a 57 merc that had a 312 but had sat for many years with out a hood,I had looked at the exhaust manifolds a couple years ago and both were cracked so I can not see any reason to take the heads off. The only parts I see that could be good would be the rocker arms.

Butchering up everything I can get my hands on in Dayton Ohio